There will be a preliminary audit at first, and then normally a full-blown audit once the contract is given. It's a competitive process, so every firm has to file its proposal of the measures they favour, what the payback period is, and so on. All the firms present their different strategies based on their assumptions and based on their evaluation of the current building. One might propose a ground-source heat pump and the other might propose some other technologies to achieve cooling and space heating savings.
On March 9th, 2017. See this statement in context.